Linings or casings for tunnels, galleries, mine pits and the like

ABSTRACT

Casings acting as circular-section revetments or coverings of cavities formed in the ground to resist the thrust of the ground; in said casing, a panel which adapts itself to the ground it must cover and which has an arcuate web bordered by inner flanges constituting a roughly rectangular frame, the web havong a meridian sectional shape having an outer bulge, the web being extended laterally by a frustoconical portion which is outwardly divergent and extends beyond the frame and defines a socket rabbet for assembly with a panel od an adjacent casing ring; the panel comprises, on one of the transverse flanges of its frame, at least one rib for assembly with an adjacent panel of the same casing panel and, in the transversely opposed flange, a support recess correspondint to and cooperating with said rib.

United States Patent Leblond et a1.

[54] LININGS OR CASINGS FOR TUNNELS,

GALLERIES, MINE PITS AND THE LIKE [72] Inventors: Christian Georges Leblond, Atton;

Jacques Francois Marie Oger, Pont- A-Mousson, both of France [73] Assignee: Centre De Recherches De Pont-A- Mousson, Maidieres, Pont-A-Mousson, France 22 Filed: Aug. 25, 1969 21 App1.No.:8 52,602

[30] Foreign Application Priority Data Aug. 27, 1968 France ..68164222 .52 US. (:1. ....6 1/45 R, 61/42 51 1111.01. ..E2ld 11/14 58 Field 6: Search ..61/45, 42, 84, 85, 43, 63

56 References Cited UNITED STATES PATENTS 1,284,099 11/1918 Harris ..61/45 R ux 1,969,810 8/1934 McAlpine ..61/45 R 413,384 10/1889 Beecher ..61/45 ux 834,745 10/1906 MOif ..61/85 935,376 9/1909 Lennon ..61/45 1,047,983 12/1912 Phelan ..61/45 ux 1451 Jan. 2, 1973 1,397,708 11/1921 Stowell .......61/45 X 1,853,224 4/1932 Proctor ..61/45 1,923,007 8/1933 Proctor ..6 l /45 3,411,826 11/1968 Wallers et al. ..61/35 X 3,438,211 4/1969 Zywietz eta1. ..61/45 FOREIGN PATENTS OR APPLICATIONS 348,421 10/1960 Switzerland ..61/45 Primary Examiner-Dennis L. Taylor Att0meyJ. Delattre-Seguy ABSTRACT Casings acting as circular-section revetments or coverings of cavities formed in the ground to resist the thrust of the ground; in said casing, a panel which adapts itself to the ground it must cover and which has an arcuate web bordered by inner flanges constituting a roughly rectangular frame, the web havong a meridian sectional shape having an outer bulge, the web being extended laterally by a frustoconical portion which is outwardly divergent and extends beyond the frame and defines a socket rabbet for assembly with a panel od an adjacent casing ring; the panel comprises, on one of the transverse flanges of its frame, at least one rib for assembly with an adjacent panel of the same casing panel and, in the transversely opposed flange, a support recess correspondint to and cooperating with said rib.

13 Claims, 14 Drawing Figures LININGS OR CASINGS FOR TUNNELS, GALLERIES, MINE PITS AND THE LIKE Each panel generally comprises an arcuate web whose curvature corresponds to that of the circular section of the casing, this web being borderedby flanges eonstituting a roughly rectangular frame. The panels are assembled by bolts extending through the flanges which face inwardly of the casing and are applied against one another, Their assembly is completely rigid, both during assembly and when the assembly is finished. Therefore, inevitably, the casing adapts itself imperfectly to the ground and that a large annular gap exists between the'wall of the cavity formed in the gr ound and the outer face of the casing; This gap must be filled with cement or concrete. Further, the casings of this known type, necessarily have a cylindrical shape with rectilinear generatrices owing to the rigid assembly of panels consisting of cylindrical sectors.

The object of the invention is to provide a casing panel which is so improved as to adapt itself to the ground it must cover,-torcduce to a minimum or do away with the cement or concrete filling or jointing and to pennit curved casings to be constructed.

The invention provides a panel of the type having an arcuate web bordered by inner flanges constituting a roughly rectangular frame, wherein the web has a meridian sectional shape having an outer bulge and is extended laterallyby a frustoconical portion which is outwardly divergent and extends beyond the frame and defines a socket rabbet for assembly with a panel of an I adjacent casing ring.

According to another feature of the invention, the improved panel comprises, on one of the transverse flanges of its frame, at least one ribfor assembly with an adjacent panel of the same casing panel and, in the T transversely opposed flange, a support recess corresponding to and co -operable with said rib.

Another object of the invention is to provide a specialexpansible panel which is adapted to terminate a casing ring, this panel being expansible in its cross section owing to the fact that it comprises two superimposed elements which are slidable relative to each other, the upper element being without a transverse flange at the end which caps the lower element, means being provided for fixing one of said elements relative to the other of said elements so as to render the panel rigid in the selected arcuate length thereof.

Another object of the invention is to provide an improved casing of the aforementioned type, wherein each of its rings is constituted by the assembly of the improved panels and the expansible panel specified herein before, these panels being wedged relative to each other, the rib of one being applied in the cooperable recess of the adjacent panel whereby each panel has, in the axial direction, on one side, a male outer circular face which is roughly continuous and, on

the other side, a frustoconical circular inner face which is roughly continuous and constitutes a socket rabbet,

said rings being assembled together by the engagement of the outer male face of each thereof in the rabbet of the adjacent ring.

Owing to these features, the casing rings are capable of being fitted or engaged together to 'a variable depth and this enables them to be better applied against the wall of the cavity to be covered. Furthermore, the rings can be mounted at a certain angle to each other, and

this enables the casing to be constructed with broken generatrices.

Thus, instead of being rigid in the course of assembly as in the known technique, the casing according to the invention has a certain flexibility which enables it to adapt itself to the ground while being perfectly integral therewith once the assembly is finished. 1

Further features an advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings.

FIG. 1 is a diagrammatic perspective view of an' ordinary casing panel according to the invention;

FIG. 2 is a detail viewon an enlarged scale, of an assembly of two consecutive ordinary casing panels;

FIG. 3 is a perspective and sectional view .of an expansible panel;

FIG. 4 is a partial cross-sectional view of a casing ring;

FIG. 5 is a partial detail view taken along line 5-5 of FIG. 4;

FIG. 6 is a diagrammatic perspective view of a portion of a casing according to the invention;

FIG. 7 is a longitudinal sectional view of a portion of a casing according to the invention;

FIG. 8 is a sectional view of an assembly of two panels having a modification of the assembly ribs;

FIG. 9 is an end elevational view of the co-operating ribs;

FIG. 10 is a plan view of an improved modification of an expansible panel;

FIG. 11 is a cross-sectional view, taken along line llll of FIG. 10, that is, in a plane perpendicular to the axis of the casing of the expansible panel assembled with the neighboring panels of the same casing ring;

FIG. 12 is a sectional view taken along line l2l2 of FIG. 10 with a part cut away and in perspective, of an expansible panel according to the invention, assembled with neighboring panels of two adjacent rings;

FIG. 13 is a cross-sectional view, taken along line I3I3 of FIG. 12, of the assembly of the male portion of the expansible panel and the socket of an ordinary panel, this view illustrating the continuous male assembly face, and

FIG. 14 is a cross-sectional view, taken along line l 4-l4 of FIG. 12, of an assembly of the female portion of an expansible panel and the male portion of a neighboring ordinary panel, this view also illustrating the continuous female assembly face.

According to the embodiment shown in FIGS. 1 and 2, the ordinary casing panel P improved in accordance with the invention consists of a generally arcuate body of spheroidal graphite cast iron. It comprises a'web 1 (FIG. 2) whose radius of curvature corresponds to that of the cylindrical section of the casing to be constructed.

This web 1 is bordered by rectilinear transverse flanges 2 parallel to the axis of the casing to be constructed and arcuate flanges 3 which constitute with the flanges 2 a roughly rectangular frame. The are of the web I is a sub-multiple of 360, equal to 360/n, ifn arcuate panels P are required to form a complete casing ring.

This flange 1 of the panel P has a meridian sectional shape including a bulge constituted by two frustoconical portions or faces 4 and 5, which are convergent toward the axis of the inner concave face of the panel but have opposed conicities, and a median cylindrical portion or face 6 interconnecting the faces 4 and 5. The outer bulge of the web 1 therefore has a trapezoidal sectional shape.

The web 1 is extended by a third frustoconical portion 7 which is located outside the frame constituted by the flanges 2 and 3 and is therefore in overhanging relation thereto. This portion 7 defines a socket or fitting rabbet in a complete ring of said panels. It has an outwardly divergent frustoconical inner or female face having the same conicity as the frustoconical outer or male face 4, the smaller end of the portion 7 being connected to the smaller end, of equal diameter, of the adjacent face which has an opposite conicity. The faces or portions 5 and 7 thus define an annular outer recess.

The panel P has keying means in the form of an assembly rib or tongue 8 on one of the rectilinear flanges 2 of the frame. This rib follows the trapezoidal profile of the web and even extends along the edge of the frustoconical portion 7. The opposite rectilinear flange 2 has a recess 9 corresponding to the rib 8 for the assembly of the neighboring panels (FIG. 2).

Further, a sealing bead 10, for example of an elastomer, is disposed on each side of the rib or tongue 8 so as to surround it. Another sealing bead 11 is applied against the frustoconical portion 4 near the neighboring arcuate flange 3. The bead 11 matches the curvature of the panel and is orthogonal to the first two beads 10. The beads 10 and 11 are vulcanized or stuck to the rough cast face of the panel. The sections of the beads 10 and 11 are such that they are crushed against the walls of the assembled panels so as to afford a seal, as shown in FIG. 2 in respect of the beads 10.

Stiffening ribs or gussets are provided in the known manner for rendering the web 1 rigid by the support afforded by the transverse flanges 2 of the frame.

According to the invention, there is also provided a special expansible panel P for completing the casing ring which is thus formed by n-l panels P and one panel P (FIGS. 4, 6 and 7).

This panel P is expansible in the direction of its cross-section, that is in the direction of its arcuate length. For this purpose, it comprises (FIGS. 3 and 4) two superimposed elements, namely an outer element 13 and an inner element 14 which are relatively slidable. The element 13, has a single rectilinear transverse flange 2, the opposite transverse flange having been omitted to allow the passage of the element 14. The inner face of the element 13 acts as a slideway for the web of the element 14.

This element 14 has rectilinear transverse flanges 2, one of them being adapted to be disposed inside the element 13 and having neither a recess 9 nor a rib 8 and the other being adapted to assembly with a normal panel A and having a rib 8 for this purpose.

The flanges 2 are shorter than the flanges 2 of the ordinary panels P so that the inner edge of the frame, in the radial direction is aligned with the other edges of the frame and does not project inwardly. Further, a sealing bead 15 (FIGS. 4 and 5) is so disposed as to be parallel with the flanges 2 on the web of the element 14. It is adapted to be crushed against the inner face 16 of the element 14 so as to afford a seal with the slideway. If 360/n is the angular extent of an ordinary panel P, that of an expansible panel P can vary within the limits (360/n) L and (360ln) L.

The expansible panel P is adapted to be the last to be assembled or mounted between two ordinary panels P so as to complete one casing ring. Owing to the substantially telescopic assembly of the elements 13 and 14, the element 14 can be introduced inside the element 13 so as to have a total arcuate length less than the free arcuate length existing between the last two ordinary panels P of a given casing ring (FIG. 4). The panel P is thus easily introduced in this free space. Then, through the agency of a thrust jack V placed between the rib 2 of the element 13 and the rib 2 of the element 14, which has no assembling means, the rib 8 of the element 14 is applied in the recess 9 of the neighboring panel P. The possible expansion or contraction of the panel A of an arcuate length L makes it possible to take up manufacturing tolerances in the arcuate lengths of the rough cast panels and above all the tolerances in the cavity formed in the ground.

After the expansible panel P has been adjusted, the two elements 13 and 14 are fixed in their adjusted positions by means of bolts 17 (FIG. 4) which extend through the arcuate flanges 3. Instead of employing bolts 17, merely blocks, replacing the jack V, could be employed.

A complete casing is constructed (FIGS. 2, 4, 6 and 7) with panels P and P in the following manner:

Two panels P are assembled in such a way that the rib 8 is fitted into the co-operating recess 9. As the transverse rectilinear flanges 2 of the frame are not exactly radial but oriented in such a manner as to make an angle x of less than (FIG. 4) with a plane tangent to the web 1, a clearance is formed between two neighboring flanges 2 and the combination of the tongue 8 and the recess 9 constitutes a pivot about which the neighboring panels P can pivot in the course of assembly. This pivot is locked in position, at the end of the assembly of the casing rings, by the locking of the last panel, namely the expansible panel P and by the alternation of the junction lines 18 (FIG. 7) of the panels, so that the pivotal junction lines 18 are capped by the frustoconical portions 7 of the neighboring panels.

The assembly of n-l panels P having a total arcuate extent or length 360P and a special expansible panel P constitutes a complete casing ring, only a part of which is shown in FIG. 4. In this assembly, the sealing rings 10 are compressed between the flanges 2 of the neighboring panels P and afford a seal in the radial direction.

Two adjacent rings are assembled by introducing the male frustoconical portions 4 of one ring in the rabbet defined by the extension portions 7 of the adjacent ring (FIG. 4). It is the sealing bead 11 which, as it is compressed between the socket 7 and the male frustoconical portion 7, affords the seal. If the penetration P (FIG. 7) of the male portion 4 in the socket 7 is uniform throughout the perimeter of the rings, a rectilinear assembly having an axis XX is obtained. On the other hand, if a casing having a broken axis XX-Y is required, the penetration of the portion 4 in the socket 7 is varied along the periphery, the maximum penetration being diametrally opposed to the minimum penetration. In the minimum penetration region a wedge or block 19 is introduced so as to render the assembly more rigid. The assembly can be thereafter fixed by bolts extending through adjacent arcuate flanges 3 and the block 19 inserted between these flanges 3. p

In practice, a casing is assembled inthe following manner:

The cavity to be provided with the casing having been formed in the ground in a roughly cylindrical shape the casing panels P and P being supplied with their sealing beads, these panels are mounted in the cavity in the following manner:

A first panel P is placed on the lower part of the cavity (gallery or tunnel) directly on the ground. Then the following pannels P are fitted in succession by introducing the ribs 8 into the recesses 9 and suitably applying the panels against the ground while holding them as the assembly progresses along the walls of the cavity. In this way there is constructed, panel by panel, a casing ring whose last element is the expansible panel P 1 which is therefore in the upper part of the tunnel. The panel P is shortened to the maximum extent by a relative sliding of the elements 13 and 14 in order to introduce it between the two neighboring panels P and then expanded to the maximum extent by means of the jack V so as to be assembled between the neighboring panels P and applied against the wall of the tunnel. The expansible panel P is thereafter fixed at its final length, for example by means of bolts 17 (FIG. 4) as explained herein before. The pivotal connections between the panels, constituted by the ribs 8 and the recesses 9 are rendered rigid after complete assembly of the ring and of the neighboring rings owing to the staggering of the junction lines 18 (FIG. 7). v

To mount the following casing ring, its first panel P is placed on the ground in fitting the male frustoconical portion 4 in the conical socket ,7 of the neighboring panel of the first ring. However, it is arranged that the panel of the second ring is circularly offset relative to the corresponding panel of the first ring so that the junction or joint lines 18, are not in the extension of one another in the successive ringsbut staggered relative to one another. The panels are then continued to be mounted or assembled as previously explained.

When the second ring is finished, it is wedged relative to the first ring by means of blocks 19 in the chosen position of uniform penetration throughout the peripheral extent, as in the case of the part of the casing corresponding to axis XX in FIG. 7 or, of variable penetration as shown in the part of the casing corresponding to axis XY in FIG. 7. Bolts 20 are then inserted and tightened so-as to prevent the rings from coming apart. v I

The advantages of the invention are the following:

Owing to the bulging shape of the web 1, the panels P or P have considerable rigidity and offer high resistance to the thrustof the ground and are yet very light.

Owing to the male frustoconical portion 4 and the frustoconical socket portion 7, the panels of the neighboring rings fit together with flexibility and thus constitute a flexible assembly in the course of mounting the panels, this assembly becoming rigid when the mounting is finished.

A variable penetration of one ring in the neighboring ring enables a curved casing to be constructed. Thus for an inside panel diameter of more then 6 meters, it is possible to achieve casing curves having a minimum radius of meters in any direction.

The overlapping of the joint lines 18 of the panels by the frustoconical portions 7, owing to the alternation of the joint lines ensures that the assembly is perfectly rigid when finished, whereas in the course of assembly, the assembly has a certain flexibility.

Owing to the special contractable and expansible panel P, a casing ring is very easy finished by lastly employing a panel P to take up the tolerances in the diameter of the cavity formed in the ground and the manufacturing tolerances of the panels P.

I Owing to the ribs 8 and the corresponding recesses 9, the panels P of a given ring are in a certain way pivoted together and this enables them to be adapted to the ground and marry up with the wall of the cavity formed in the ground and leave the minimum annular empty space to be filled with cement. Further, the assembly of the panels is sufficiently precise to achieve a roughly continuous outer face of the rings.

Owing to the various sealing beads, the waters of the earth cannot enter the interior of the casing and this enables the work to be carried out under improved conditions of comfort, hygiene and safety.

The panels P and P have, moreover, shapes which are so designed that the panels can be employed directly as cast. Y

Owing to the ribs 8, the recesses 9 and the frustoconical portions 4 and 7, the various panels can be assembled without error and easily.

In the assembled casing (FIGS. 6 and 7) the succession of the frustoconical portions 4, 5 and 7 and the cylindrical faces 6 creates alternating bulging parts and hollow parts which form a sinusoidal shape which particularly contributes to the strength of the casing.

Owing to the fact that-the panels fit into one another, as concerns both the frustoconical portions and the ribs and recesses, the assembly can be achieved with much less bolts than in casing panels of known type, since only the fixing means, such as the bolts 20, are essential to prevent the rings from coming apart. The difficulties of the alignment of the bolt holes are consequently reduced.

According to modifications:

The blocks 19 and the bolts 20 can be omitted and replaced by stirrups 21 (FIG. 7) which damp together the adjacent arcuate flanges 3 of neighboring rings. This arrangement has the advantage of rapid assembly.

- The co-operating ribs 8 and recesses 9 can be replaced by keying means in the form of ribs 22 and complementary ribs 23 of the panels P and P respectively (FIG. 8) which are adapted to be superimposed on one another so as to constitute reciprocal supports. These ribs can be carried by the flanges 2 having a crooked face having hollows and projections so as to follow the shapes of the ribs 22 and 23, which increases the strength of the assembly.

The ribs can be discontinuous and stepped as shown at 22", 22, 22 and 23, 23", 23 in FIG. 9 where the ribs 22 pertain to keying means on the panel P and the ribs 23 (shown in dot-dash lines) pertain to the complementary keying means on adjacent panel (not shown).

In FIGS. -14 there is shown a modification of a special panel of the type described herein before but improved in such a manner as to be capable of being adjusted in a continuous manner through its expansible arcuate faces on the normal panels or arch members of the neighboring rings, irrespective of the expansion position of one of the elements which is superimposed relative to the other, so as to afford a sealed assembly. In this special expansible panel, the frustoconical female portion of the outer element and the frustoconical male portion of the inner element have at their ends, respective ribs respectively facing inwardly and outwardly and extending to the extension of the inner or outer arcuate face respectively of the female portion of the inner element and of the male portion of the outer element.

Each of these ribs thus extends the arcuate socket face of the co-operating portion of the other element and this improves the fitting conditions between the expansible panel and the neighboring panels of the adjacent rings of panels.

According to this embodiment shown in FIGS. 10-14, the expansible panel P, comprises, as in FIGS. 3 and 4, two superimposed elements or arch members, namely an outer or upper element 13 and an inner or lower element 14 which are relatively slidable. Both are bodies of spheroidal graphite cast iron. They comprise an arcuate web 1 or 1 bordered by two transverse flanges 2 or 2, the lower element further comprising two longitudinal arcuate flanges 3. Their webs 1, 1" have a generally arcuate shape. Their meridian sections (FIG. 12), namely their sections in a radial plane 12 12 (FIG. 10) intersecting the axis of the cylindrical casing and normal to the curvature of the panel are roughly trapezoidal. Indeed, the web 1 of the outer arch member 13 comprises, as in the preceding embodiments, a cylindrical portion 6 adjoined by two frustoconical portions 4 and 5 which are convergent toward the axis of the casing and have opposite conicities and serve to stiffen the panel. The frustoconical portion 4 is male and adapted to fit in the co-operating female portion 7' of a neighboring panel P of a first adjacent ring of panels. The portion 5 is extended by a female frustoconical portion 7 having the same conicity as the portion 4 so as to serve as a socket for the cooperating male portion 4' of a neighboring panel P of the second adjacent ring of panels. Further, the web 1" of the inner or lower arch member 14 has a cylindrical portion 6 and frustoconical portions 4, 5, 7, the portion 4 being male and the portion 7 female for the purpose of assembly with neighboring panels. These portions have the same conicities as the respective portions 4, 5 and 7 of the arch member 13.

The portion 7 of the outer element 13 is bordered by a rib 24 which is inwardly projecting. The projection of this rib has a value roughly equal to the thickness of the corresponding portion 7 of the inner element 14 so as to be in the extension of the inner face of the socket of the latter and form therewith a socket face S. Furthermore, this inner rib 24 is spaced from the end face of the portion 7 of the inner element so as to form a recess for a sealing element 25 constituted by an elastically-yieldable bead which, in its free condition, projects from the face S.

Further, the male frustoconical portion 4 of the inner element 4 is bordered by an outwardly projecting rib 26 which projects to an extent roughly equal to the thickness of the corresponding portion 4 of the outer element 13 so as to be in the extension of the male outer face for assembling the element 13 and form therewith an assembling face S. It also forms with the end face of the portion 4 a recess for a sealing element 27.

The sealing elements 25 and 27 afford a seal on the respective arcuate contact faces S and S with the neighboring panels 1" and P of the adjacent rings of panels.

The inner elements 14 is fixed to the outer element 13 by bolts 28 which extend through apertures 29 in the web 1 and openings 30 in the web 1".

Owing to the openings 29 and 30 in the webs 1 and 1 of the elements 13 and 14 an inner sealing plate 31 is attached in a sealed manner inside the element 14, below the web 1 and parallel to the latter by screws 32.

In cross-section, that is, in a direction perpendicular to the axis of the casing (FIG. 11), the elements 13 and 14 have assembling ribs 22 and 23 similar to those shown in FIG 8 for assembly with neighboring panels P and P of the same ring, and the same sealing element The assembly with two normal panels P and P pertaining to neighboring rings (FIG. 12) is effected by introducing the male frustoconical portion 4 of the outer element 13 and the rib 26 of the inner element 14 under the corresponding socket portion 7 of the panel I" of the neighboring ring and introducing male frustoconical portion 4 of the panel P of the other neighboring ring under the socket portion 7" of the inner element 14 and the rib 25 of the outer element 13. The sealed contact is achieved on the faces S and S (FIGS. 13 and 14) and with sealing elements 27 and 25 independently of the adjustment of the element 14 relative to the element 13.

As shown in FIGS. 13 and 14, the assembling faces S and S are adjusted in a continuous manner on the portions of the neighboring panels P and P irrespective of the adjustment of the extension of the expansible panel P.

It is therefore easy to achieve a complete seal relative to the outside waters irrespective of extension of one of the elements relative to the other, by providing for the expansible panel I" in addition to sealing elements 25 and 27 between the elements 13 and 14, other sealing elements at 33 in the element 14 which come in contact with the inner face of the element 13; at 10 in the outer face of the portion 4 which comes in contact with the portion 7 of the panel P adjacent the sealing element 27 and at 34 under the portion 7 which comes in contact with the portion 4 of the pannel P adjacent the sealing element 25.

This complete sealing off from outside waters is achieved entirely by the sealing elements which are vulcanized or stuck to the elements 13 and 14 in the factory when they are manufactured.

Indeed (FIG. 13):

The rib 24, the sealing element 25, the female portion 7" of the inner element 14 and the sealing element 34 are fitted on the male portion 4 of the adjacent panel P in a sealed manner and continuously irrespective of the expansion of the expansible panel P,.

The rib 26, the sealing element 10 of the outer element 13, the sealing element 27 of the inner element 14 and the male portion 4 of the element 13 fit under the female portion 7 of the adjacent panel P in a sealed and continuous manner, irrespective of the expansion ofthe panel P'j.

The sealing element 33 of the element 14 affords a seal between the two elements 13 and 14 irrespective of the expansion of the panel P The sealing elements 10 and the rib 22 of the outer element 13 and the rib 23 of the inner element 14. seal the'fitting together with the neighboring elements of the same casing ring (FlG. 2) in combination with the sealing elements 10.

The plate 31 closesin a sealed manner the inner element 14 which is perforated by the three slots 30 for the passage of the fixing bolts 29.

The complete seal thus achieved also enables concrete to be injected outside the casing between the latter and the cavity formed in the ground with no possibility of this concrete entering the casing.

Sealing elements may also be provided embedded in the male and female assembly portions of the adjacent panels P and P.

' Although specific embodiments of the invention have been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Thus the web 1 having a bulge can be dished in the manner of a barrel, that is, have a curved convex profile instead of a trapezoidal profile. In this case, the curved profile is a portion of a sphere centered on the axis XX of the casing and tangent to the inner frustoconical socket face 7 of a neighboring panel.

Further, instead of being cast metal alloys such as spheroidal graphite cast iron, the panels can be of bent and welded sheet metal.

Although only the bolts or stirrups 21 (FIG. 7) are essential to prevent the rings of the casing from coming apart, bolts could also be employed for assembling the panels P by clamping together the rectilinear flanges 2. The use of bolts can be of utility in the case of very high bending moments.

An expansible panel P can be replaced by a special panel of known type termed a key, whose frame flanges 2 are parallel instead of being radial. Such a key is combined with counter-keys. However, a key does not have the advantages of the expansible panel P.

What we claim is:

l. A segmental arcuate panel for the construction of a casing having a cylindrical cross-sectional shape, said panel comprising a generally part-cylindrical web curved about an axis and two first flanges extending substantially in planes perpendicular to said axis and two second flanges extending substantially in axial planes containing said axis, said flanges being integral with and extending from said web toward said axis and constituting a frame, said web having a first arcuate frustoconical portion defining an outer frustoconical male face adjacent one of said first flanges and, extending throughout the circumferential extent of said panel, a second arcuate. frustoconical portion adjacent the other of said first flanges, an intermediate portion interconnecting said frustoconical portions, said first portion and said second portion having opposite conicities and being convergent toward said axis and a third arcuate frustoconical portion extending said web axially of said axis and outwardly divergent from said second portion relative to said axis and extending beyond said other first flange and defining an inner frustoconical female face extending throughout the circumferential extent of said panel and having such conicity and radius of curvature as to be capable of axially fitting around the male face of an identical panel.

2. A panel as claimed in claim 1, wherein one of said second flanges has keying means and another of said second flanges has keying means complementary to the keying means on said one of said second flanges whereby said complementary keying means is capable of circumferentially engaging the keying means on said one of said second flanges of an identical panel, said keying means of said two second flanges being arranged to permit assembly of said identical panel with said panel in circumferential alignment in a single plane perpendicular to said axis and to substantially preclude relative movement between the assembled panels radially of said axis.

3. An arcuate panel for the construction of annular assemblies of a plurality of said panels, said panel comprising an arcuate rectangular web portion extending circumferentially about an axis and having a shape which is substantially inscribed in a portion of a spherical surface which is centered on said axis and including at one end of said web a first marginal arcuate frustoconical portion defining an outer frustoconical male face extending throughout the circumferential extent of said panel, and at an axially opposed end of said web a second arcuate frustoconical portion axially extending said web portion and having substantially the same conicity as said first portion and defining an inner frustoconical female face extending throughout the circumferential extent of said panel, said frustoconical faces having substantially identical mean radii so that a first annular assembly of a plurality of said panels can be axially fitted in a second annular assembly of a plurality of said panels by fitting the male faces of the panels of said first assembly in the female faces of said second assembly, said panel having two axially extending edge portions circumferentially defining said panel, first keying means on a first of said edge portions and second keying means on a second of said edge portions, said keying means having such shapes as to be mutually engageable whereby when said first edge portion of said panel is circumferentially engaged with the second edge portion of an identical panel in said annular assembly the two panels are keyed together, said keying means being arranged to exert a keying action in a radial and in an axial direction so that said panel can be maintained in alignment with adjoining panels in said assembly in both radial and axial directions, said axially extending edge portions having such configuration as to permit pivotal movement of said panel with respect to a circumferentially adjoining identical panel in said assembly in a plane perpendicular to said axis, and radial bearing faces in regions of said panel adjacent said first frustoconical portion and said second frustoconical portion for receiving means maintaining said panel in axial position relative to axially adjacent identical panels.

4. A casing panel as claimed in claim 1, wherein the panel further comprises first keying means defining a rib on one of said second flanges, second keying means defining a bearing face on another of said second flanges and having a shape substantially matching and complementary to the shape of said rib, first sealing bead means extending axially alongside one of said keying means and adapted to be put under circumferential pressure upon assembly of said panel with an identical panel in a common plane perpendicular to said axis and second sealing bead means on said male face and extending circumferentially of said male face in the vicinity of said one first flange.

5. A panel as claimed in claim 2, wherein said two keying means extend throughout the axial extent of said panel.

6. A panel as claimed in claim 1, wherein one of said second flanges has a face including projections and hollows and another of said second flanges has a face including hollows and projections which are adapted to lock radially and axially with said projections and hollows on said one of said first flanges of an identical panel.

7. A panel as claimed in claim 6, wherein said one of said second flanges comprises rib portions which are offset from rib portions on said other of said second flanges radially of said axis so as to constitute discontinuous reciprocal bearing faces for two of said panels when assembled.

8. A panel as claimed in claim 2, comprising a first axially projecting sealing element extending throughout the length of an axially extending edge portion of said panel and a second sealing element on one of said frustoconical male and female faces and extending throughout the circumferential length of said one of said male and female faces.

9. An expansible panel for use in the construction of a casing having a cylindrical cross-sectional shape, said panel comprising an inner member and an outer member which are adjoining, overlapping and relatively slidable and means for fixing one of said members to the other member, said outer member comprising a generally part-cylindrical web curved about an axis, said web comprising a meridian portion having an outer bulge and including at one axial end a marginal first frustoconical portion defining an outer outwardly eonvergent frustoconical male face, and a second frustoconical portion extending from another axial end of said meridian portion axially of said axis and outwardly divergent relative to said axis, said inner member comprising a web having a meridian portion having an outer bulge and including at one axial end a marginal first frustoconical portion, and a second frustoconical portion extending from another axial end of said meridian portion of said inner member axially of said axis, said meridian portion and said frustoconical portions of said inner member substantially matching said meridian portion and said frustoconical portions of said outer member, said inner member comprising two first flanges extending in diametral planes intersecting said axis and two se 0nd flanges extending in axial planes containing sat axis, sai second frustoconical portion of said inner member extending axially beyond one of said first flanges and defining an inner female frustoconical face having substantially the same conicity and radius of curvature as said male face.

10. A casing panel as claimed in claim 9, comprising an axially extending sealing element on a face of said inner member adjacent said outer member.

11. A casing panel as claimed in claim 9, said panel further comprising a circumferentially extending first rib extending from an edge of said second frustoconical portion of said outer member and towards said axis substantially to the geometric extension of said inner female face of said inner member and a circumferentially extending second rib extending from an edge of said first frustoconical portion of said inner member and away from said axis substantially to the geometric extension of an outer face of said first frustoconical portion of said outer member.

12. A casing panel as claimed in claim 11, comprising a gap between each of said ribs of said members, and an end face of the adjacent frustoconical portion of the other member, sealing elements being disposed in said gaps and respectively extending beyond an outer face of said outer member and beyond an inner face of said inner member so as to afford a sealing contact with an axially neighboring panel in said casing.

13. A casing panel as claimed in claim 11, comprising a first sealing element embedded in and stuck to an inner face of said first frustoconical portion of said inner member and a second sealing element embedded in and stuck to an outer face of said second frustoconical portion of said inner member. 

1. A segmental arcuate panel for the construction of a casing having a cylindrical cross-sectional shape, said panel comprising a generally part-cylindrical web curved about an axis and two first flanges extending substantially in planes perpendicular to said axis and two second flanges extending substantially in axial planes containing said axis, said flanges being integral with and extending from said web toward said axis and constituting a frame, said web having a first arcuate frustoconical portion defining an outer frustoconical male face adjacent one of said first flanges and extending throughout the circumferential extent of said panel, a second arcuate frustoconical portion adjacent the other of said first flanges, an intermediate portion interconnecting said frustoconical portions, said first portion and said second portion having opposite conicities and being convergent toward said axis and a third arcuate frustoconical portion extending said web axially of said axis and outwardly divergent from said second portion relative to said axis and extending beyond said other first flange and defining an inner frustoconical female face extending throughout the circumferential extent of said panel and having such conicity and radius of curvature as to be capable of axially fitting around the male face of an identical panel.
 2. A panel as claimed in claim 1, wherein one of said second flanges has keying means and another of said second flanges has keying means complementary to the keying means on said one of said second flanges whereby said complementary keying means is capable of circumferentially engaging the keying means on said one of said second flanges of an identical panel, said keying means of said two second flanges being arranged to permit assembly of said identical panel with said panel in circumferential alignment in a single plane perpendicular to said axis and to substantially preclude relative movement between the assembled panels radially of said axis.
 3. An arcuate panel for the construction of annular assemblies of a plurality of said panels, said panel comprising an arcuate rectangular web portion extending circumferentially about an axis and having a shape which is substantially inscribed in a portion of a spherical surface which is centered on said axis and including at one end of said web a first marginal arcuate frustoconical portion defining an outer frustoconical male face extending throughout the circumferential extent of said panel, and at an axially opposed end of said web a second arcuate frustoconical portion axially extending said web portion and having substantially the same conicity as said first portion and defining an inner frustoconical female face extending throughout the circumferential extent of said panel, said frustoconical faces having substantially identical mean radii so that a first annular assembly of a plurality of said panels can be axially fitted in a second annular assembly of a plurality of said panels by fitting the male faces of the panels of said first assembly in the female faces of said second assembly, said panel having two axially extending edge portions circumferentially defining said panel, first keying means on a first of said edge portions and second keying means on a second of said edge portions, said keying means having such shapes as to be mutually engageable whereby when said first edge portion of said panel is circumferentially engaged with the second edge portion of an identical panel in said annular assembly the two panels are keyed together, said keying means being arranged to exert a keying action in a radial and in an axial direction so that said panel can be maintained in alignment with adjoining panels in said assembly in both radial and axial directions, said axially extending edge portions having such configuration as to permit pivotal movement of said panel with respect to a circumferentially adjoining identical panel in said assembly in a plane perpEndicular to said axis, and radial bearing faces in regions of said panel adjacent said first frustoconical portion and said second frustoconical portion for receiving means maintaining said panel in axial position relative to axially adjacent identical panels.
 4. A casing panel as claimed in claim 1, wherein the panel further comprises first keying means defining a rib on one of said second flanges, second keying means defining a bearing face on another of said second flanges and having a shape substantially matching and complementary to the shape of said rib, first sealing bead means extending axially alongside one of said keying means and adapted to be put under circumferential pressure upon assembly of said panel with an identical panel in a common plane perpendicular to said axis and second sealing bead means on said male face and extending circumferentially of said male face in the vicinity of said one first flange.
 5. A panel as claimed in claim 2, wherein said two keying means extend throughout the axial extent of said panel.
 6. A panel as claimed in claim 1, wherein one of said second flanges has a face including projections and hollows and another of said second flanges has a face including hollows and projections which are adapted to lock radially and axially with said projections and hollows on said one of said first flanges of an identical panel.
 7. A panel as claimed in claim 6, wherein said one of said second flanges comprises rib portions which are offset from rib portions on said other of said second flanges radially of said axis so as to constitute discontinuous reciprocal bearing faces for two of said panels when assembled.
 8. A panel as claimed in claim 2, comprising a first axially projecting sealing element extending throughout the length of an axially extending edge portion of said panel and a second sealing element on one of said frustoconical male and female faces and extending throughout the circumferential length of said one of said male and female faces.
 9. An expansible panel for use in the construction of a casing having a cylindrical cross-sectional shape, said panel comprising an inner member and an outer member which are adjoining, overlapping and relatively slidable and means for fixing one of said members to the other member, said outer member comprising a generally part-cylindrical web curved about an axis, said web comprising a meridian portion having an outer bulge and including at one axial end a marginal first frustoconical portion defining an outer outwardly convergent frustoconical male face, and a second frustoconical portion extending from another axial end of said meridian portion axially of said axis and outwardly divergent relative to said axis, said inner member comprising a web having a meridian portion having an outer bulge and including at one axial end a marginal first frustoconical portion, and a second frustoconical portion extending from another axial end of said meridian portion of said inner member axially of said axis, said meridian portion and said frustoconical portions of said inner member substantially matching said meridian portion and said frustoconical portions of said outer member, said inner member comprising two first flanges extending in diametral planes intersecting said axis and two second flanges extending in axial planes containing said axis, said second frustoconical portion of said inner member extending axially beyond one of said first flanges and defining an inner female frustoconical face having substantially the same conicity and radius of curvature as said male face.
 10. A casing panel as claimed in claim 9, comprising an axially extending sealing element on a face of said inner member adjacent said outer member.
 11. A casing panel as claimed in claim 9, said panel further comprising a circumferentially extending first rib extending from an edge of said second frustoconical portion of said outer member and towards said axis substantially to the geometric extension of said inner female face of said inner member and a circumferentially extending second rib extending from an edge of said first frustoconical portion of said inner member and away from said axis substantially to the geometric extension of an outer face of said first frustoconical portion of said outer member.
 12. A casing panel as claimed in claim 11, comprising a gap between each of said ribs of said members, and an end face of the adjacent frustoconical portion of the other member, sealing elements being disposed in said gaps and respectively extending beyond an outer face of said outer member and beyond an inner face of said inner member so as to afford a sealing contact with an axially neighboring panel in said casing.
 13. A casing panel as claimed in claim 11, comprising a first sealing element embedded in and stuck to an inner face of said first frustoconical portion of said inner member and a second sealing element embedded in and stuck to an outer face of said second frustoconical portion of said inner member. 